Gear train for moving picture projectors



July 23, 1935.

Original Filed Sept. l0, 1928 A. J. HOLMAN GEAR TRAIN FOR MOVING PIGTURE? PROJECTORS 3 Sheets-Sheet l July 23, 1935. A, J HQLMAN 2,008,714

GEAR TRAIN FOR MOVING PICTURE PROJECTORS Original Filed Sept. 10, 192B 5 Sheets-Sheet 2 llll IHIIIIIIII July 23, 1935. A. J. HOLMA 2,008,714

GEAR TRAIN FOR MOVING PICTURE PROJECTORS Original Filed Sept. 10, 1928 3 Sheets-Sheet 5 Patented July 23, 1935 v'Urn-TED srxlissl GEAR TRAIN FoaMovlNG PICTURE rnomc'rons Arthur J. Holman, East Orange, N. .1.V

Application September 10, 1928, Serial No. 304,977 Renewed October 24, 1934 11 Claims.

My device combines a gear train for synchronizing the movement of the illm strip and the optical rectifying meansin a projector of the type shown in my Patent No. 1,5841'098 dated May 11, 1926.

The special objects of my invention have been to reduce the total number of gears heretofore employed in a projector of this type thereby simplifying the gear `system; to reduce the number of gears between the film sprocket which actuates the film strip across the aperture plate and the revolving optical rectifying elements thereby making the synchronization of film movement and movement of optica-l rectifying elements less subject to errors arising from imperfections in the intermediate gear train; to so arrange and time the gear train that no gear shaft in the projector operates at a speed greatly in excess of the speed of the sprocket shaft thereby reducing vibration and noise to a minimum; also it has been my further object to provide an improved and simpliiied means for accomplishing the relative temporary hastening or retarding of the rotation of the illm sprocket with respect to the revolving optical system to permit framing of the picture on the screen and to permit adjustment of the aperture unit along the optical axis to compensate for film shrinkage.

My device may be best understood by reference to the accompanying drawings in which Fig. 1 is a view of a projector taken substantially on the plane of the film sprockets looking forward, with a part of the framing means removed and with the peripheries of the optical rectifying means shown in broken lines.

Fig. 2 is a plan view of a section taken on the optical axis with the shaft which carries the left optical rectifying means cut away together with the gear mounted thereon; the aperture unit being sectioned at a plane below the optical axis so as to disclose the aperture sprocket.

Fig. 3 is a section on line 3-3 of Fig. 2 illustrating the movable mounting of the aperture sprocket adjusting parts.

Fig. 4 is a diagrammatic side view showing the relative location of all gears and shafts with respect to the light source, vaperture and optical elements.

Referring now more specifically to the drawings, I is the main frame which carries the front frame 2 -secured to the main frame I by the screws 3. The front frame 2 has an integral bracket 4 in which is mounted the ball bearing 5 (Fig. 2). A similar ball bearing 6 is mounted in the upper left part of the frame 2.

A rear vertical frame 1 (Fig. 2) is suitably mounted on thev rear of the main frame I. This frame 1 carries the'ball bearings 8 and 9. Lens wheel shafts I0 and II are mounted respectively in the ball bearings 8 and 5 and 9 and 6, and carry respectively lens wheels I2 and I3 on their front 5 ends and gears I4 and I5 on their rear ends. Gears I4 and I5 are in mesh.

The gear I6 meshes with gear I 5 and is mounted on the rear end of shaft I1 which is journaled in a boss I8 on the lower portion of the back frame 1. The shaft I1 (Fig. 1) carries thereon the helical gear I9 which meshes with gear 20 on ,the power shaft 2l which receives power from a suitable source through the friction disc 22. A y wheel 23 is fast mounted on4 the power shaft 2I as is also the sprocket 24 which is used for actuating the lower magazine take-up means. The power shaft 2I is journaled in brackets 25 and 26 which are mounted on bracket 21 attached to the main frame I. 20

A sprocket bearing frame 28 is secured to the main frame I by screw 29 and to the front frame 2 by screws 30 and 3|. The lower sprocket shaft 32 is journaled in boss 33 integral with the sprocket frame. 2B and carries fast mounted on its rear end helical gear 34 which meshes with helical gear I9 on the shaft I1. The sprocket 35 is fast mounted on the front end of the sprocket shaft 32.

A vertical shaft 36 journaled in brackets 31 30 and 38 attached to the sprocket bearing frame I 28 carries fast mounted on its lower end the helical gear 39 which meshes with the helical gear 34 on the lowersprocket shaft 32. Fast mounted on the upper end of vertical shaft 38 is a helical gear 40 which meshes with a helical gear 4I fast mounted on the rear-end of upper sprocket shaft 42. This shaft 42 is journaled in boss 43 on the top of sprocket bearing frame 28 and carries fast mounted on its outer end the upper sprocket 44. 40

Sprocket bearing frame 28 has integral pads 45 and 46. l

In the same plane with pads 45 and 46 is a pad 41 which is integral with the angular bracket 5 48 fastened to the front frame 2 by the screw 49. Attached to these pads 45, 46 and 41 is a frame 50 (Fig. 2) which carries integral lugs 5| and 52. The lug 5I carries the ball bearing 53 in which is journaled the len's wheel shaft Il. 50 Within annular lug 54 on the frame'50 and annular lug 55 on the rear frame 1, are fixed respectively the front and rear ends of a tubular member 55. A similar tubular member 51 is fixed within annular lugs 58 and 59 on the bracket 55 side of the arm 86.

I and the rear frame 1 respectively. These tubular members 56 and 51 serve to brace the structure and to shield the lens wheel shafts i and I6 respectively.

The lens wheel shaft carries fast thereon a helical gear 68 (Fig. 1) for actuating the aperture sprocket 6| through the helical gear 62 by the means now to be described. A

Anvv axially -adjustable carriage 63 is slidably mounted upon rods 64 and 65 which are xed at their forward ends in the front frame 21 and at their rearends in the frame 59. The carriage 63 is stiffened by the web 66 and. carries annular bosses 61 and 68 lwhich provide sliding bearings through which pass the rods 64 and 55 respectively.

The aperture frame 69 (Fig. 2) is secured to the carriage 63 by the screws 10. The aperture frame 69 has integral bosses 1| and 12 in which is journaled the aperture sprocket shaft 13 on which is-fastA mounted the aperture sprocket 6i. The sprocket shaft 13 has an enlarged-portion 14 (Fig. l) which is bored to admit the shaft 15 with a freevsliding fit. The bore of the enlarged portion 1B is provided with key ways 16 in which engage the keys 11 which are integral with the shaft 15 and prevent any angular displacement of the shaft 15 with respect to the aperture sprocket shaft 13. The other end of the shaft anism:

'Ihe sliding carriage 63 has integral lugs 19 and (Fig. 3) within which is slidably mounted the frame 8| which bears integral circular bosses 82 and 83 which enter bores in lugs 19 and 80 respectively, and slide freely therein. The circular bosses 82 and 83 are-bored to receive the ends .of the shaft 84 which is 'slidably mounted therein. Fast mounted on the shaft 84 is a sleeve 85 which is provided with an integral arm 86 (Fig. 2) which is bored to t around the shaft 15 between a collar 81 and the gear 62 (Fig. 1) Thrust ball bearings 88 are provided on either 'Ihe sleeve 85 has attached to the top thereof by pins 89, (Fig. 3) therack bar 90 which may slide through an opening in the lug 9| on frame 8|. A pinion shaft 92 mounted to fit tightly, yet

rotatably, in the lug 9| engages the rack bar 90 and is provided with ahand wheel 93 (Fig. 2). A

coil spring 94 (Fig. 3) surrounding the circular boss 83 abuts at one end against the lug 89 and at the other end against the lug 9| on the frame 8|, thus actuating the frame 8| to the left so as to maintain the engagement of the roller 95 (Fig. 2) mounted on frame 8| with the guide track 96 on yframe 50. The guide track 96 runs at an angle to the shaft 15 equal to the angle of the teeth on the helical gear 62.

To adiust the position of the carriage 63 along the optical axis a lever 91 (Fig. 1) is provided. The lever 91 is attached at the end above its fulcrum to the lug 98 which is integral with boss 61 on the'carriage63 by the pivot screw 99. Axial adjustability of the carriage 63, is necessitated by laxial positioning of the aperture frame 69, which is secured to the carriage 63, is fullyI described in Letters Patent of the United States No. 1,857,152.

The operation of my device is as follows:

Power is applied to the shaft 2| through the friction disc 22 and thence through the gear 26 to the gear i9 and shaft |1. Thelower sprocket shaft 32 is drivenfrom the gear i9 through the gear 38 which also drives the vertical shaft 36 through the gear 39. The top sprocket shaft 82 is driven from the vertical shaft 36 through the gears 40 and lil.

Power to rotate the shafts il) and ll in opposite directions is applied by gear i6 which is fast `on the shaft |1, the gear i6 transmitting the rectifying elements, for the purpose of framng, and to permit the axial adjustment of the position of the aperture unit (iilmvshrinkage adjustment) without disturbance to "framing, power is applied to the aperture sprocket shaft 13 in the following manner:

'I'he helical gear 60 fast mounted on the shaft meshes with the long faced helical gear 62 which is fast mounted on the shaft 15 which is adjustable longitudinally, and it will be readily apparent that its movement longitudinally will i have the 'effect of either hastening or retarding the rotation of its shaft 15 and will thus have the effect of either hastening or retarding the aperture sprocket shaft 13 which is directly driven by the shaft 15 through the keys 11.

This longitudinal adjustment of the gear 62 is effected by turning the hand wheel 93 so as to move to the right or left the rack to which is connected the arm v86 which embraces the shaft 15 and fixes its longitudinal position.

It will be readily understood that if the position of the aperture frame 69 is shifted axially by movement of-its carriage 63 upon the rods 64 and 65 there will result a movement of the helical gear 62 across the face of the helical gear 60 which would result in alteration of the framing adjustment unless compensated by a longitudinal movement of the gear 62. The relative transverse and longitudinal movement of the gear62 is determined by the helical angle of the teeth of this gear. As the carriage 63 is moved forward or back by the manipulation of the lever 91 to adjust the apparatus for variations in lm shrinkage, the

ment at right angles to the movement imparted to the carriage 63. This movementy of the frame 8| is automatically regulated by the contact of the roller with guide track 96 which isaligned at the same angle with respect to the optical axis as that of the teeth on the helical gear 62. The constant bearing of 'the roller 95 on the guide track 96 is -maintained in every position by the pressure of the coil spring 94 which forces the frame 8| to the left. 'I'he pinion shaft 92 `is frictionally retained in the b'oss 9| -to an extent such that no rotation thereof is possible except 'by substantial torque being appliedI to the hand matic side view of my gear train in association with a light source of the reflector type, the light source being located at III so that the light rays |I impinge upon the reflector |02 and are re- .ilected forward through the condenser |03, which converges the light beam through the optical system after passing the aperture plate position indicated by the curved broken line |04, whence it finally passes through the objective |05. Thus it will be seen that my improved gear train embraces the lamp house, and permits a direct drive between the revolving lens wheel shafts without interference with the light beam. In this'diagrammatic view shown in Fig. 4 are also indicated the lower magazine shaft |06 and the sprocket lill for actuating the film take-up reel through the medium of sprocket chain |08, which is driven by the sprocket 24, which has been previously described. v

From the foregoing, it will be readily apparent that there are many advantages in the above described structure as compared with that disclosed in my said Patent No. 1,584,098.- As the gear train is employed in a situation such that -it is important to eliminate vibration and wear as much as possible, and also important to minimize as much as possiblethe results of slight imperfections in the gear teeth, the gear train' above described is especially adapted for service under the conditions for which it is designed to be used. 'I'he synchronized elements, including the two revolving lens wheels and the aperture sprocket, are driven as a unit from a shaft which has been made practically free from speed pulsations. The revolving lens wheels are driven directly, the one from the other, through a single pair of gears and one rolling gear contact; any error, therefore, in the synchronization of these lens wheels is due to an inaccuracy of the manufacture of the two gears only. There is no chance for cumulative error to creep in. Since these gears are identical, the\manufacturing problem has been reduced to a minimum, as only one kind `of precision gear is required to obtain exact synchronization of the revolving lens wheels.

The drive from one revolving lens wheel shaft to the-aperture sprocket is provided through a single pair of helical gears which are inherently smooth running and quiet. 'Any error in synchronizing the movement of the film strip with the rotation of one of the revolving lens wheels is due to the inaccuracy of two gears only, whereas, in the design shown in my said patent, there were seven gears in the train from a lens wheel to the aperture sprocket and thus the opportunities'for error were multiplied.

The means provided to frame" the picture on the screen and at the same time, permit moveyment of the aperture unit along the optical axis preferable to employ the construction shown.

'I'he simplicity and cheapness of my improved structure is apparent.

.'InFigAofthedrawingsisshownadiagram- Having thus fully described my invention, what I claim is:

1. In a moving picture device employing overlapping rotatable rectifying elements, the combinationv of a power shaft, a gear fast mounted thereon, a second gear meshing with said gear fast mounted on said power shaft, a second shaft to one end of which said second gearvi's attached,

a third gear attached to the opposite end of said second shaft, .a pair of parallel shafts carrying upon one end of each an optical rectifying element, and a pair of similar gears each of which is fast mounted upon one of said parallel shafts .on the end thereof opposite to said end upon which said optical rectifying element may be mounted, -which similar gears mesh with each other and one of which gears meshes with said third gear.

2. In a moving picture device employing overlapping rotatable rectifying elements, the combination of a pair of parallel shafts adapted to carry a pairA of optical rectifying elements on their forward ends, and a pair of similar gears, said gears being fast mounted on the rearward ends of said parallel shafts, and arranged to mesh with each other, the point of contact of the pitch circles of said gears being on the optical axis and behind the light source substantially as and for the purpose specified.

. 3. In a moving picture device employing overlapping rotatablerectifying elements, the combination ofa pair of parallel shafts carryinga pair of optical rectifying elements, a pair of similar gearsfast mounted on said pair of parallel shafts and arranged to mesh with each other, a

third gear fast mounted on one of said parallel shafts, a fourth gear arranged to be driven by said third gear, a third shaft rotatably and slidably mounted for adjustment axially and having fast mounted thereon said fourth gear, an aperture film sprocket, means for driving said sprocket from said third shaft, means for moving said third shaft and said film sprocket in a direction parallel to said parallel shafts, and means for moving simultaneously said third shaft in an axial direction to prevent change in relative angular velocity of said third and fourth gears as said film sprocket is thus moved.

4. In a device of the character specified, the combination of a pair of parallel shafts carrying a pair of optical rectifying elements, a pair of similar gears fast mounted on said pair of parallel shafts and arranged to mesh with each other, a third gear fast mount-ed on one of said parallel shafts, a fourth gear arranged to be driven by said third gear, a third shaft rotatably and slidably mounted for adjustment axially and having fast mounted thereon said fourth gear, an aperture film sprocket, means for driving said sprocket from said third shaft, and means for moving said third shaft in an axial direction.

5. In a device of the character specified, the combination of a pair of parallel shafts carrying a pair of optical rectifying elements, va pair of similar gears fast mounted on said pair of parallel shafts and arranged to mesh with each other, a third gear fast mounted on one of said parallel shafts, a. fourth gear arranged to be driven by said third gear, a. third -shaft rotatably and slidably mounted for adjustment axially and having fast mounted thereon said fourth gear, an aperture film sprocket, means for driving said sprocket from said third shaft, means for moving said third shaft and said hlm sprocket in a direction parallel to said parallel shafts, means for moving 75 i simultaneously said und man in sa anni sneevtion 'to prevent change in anguler velocity of said shafts, a third shaft rotatably and slidabiy mounted on said carriage, a fourth gear fast mounted on said third strait and arranged to rnesn with and be driven bv said third gear, an aperture nlm sprocket rotatably mounted on said carriage in alignment with said third shait and adapted to be driven thereby, means for main taining driving engagement between said third shaft and said sprocket, and means for preventing change in angular velocity oi said sprocket as said carriage is adjusted withrespect to said rectifying elements.

7. In a gear train for a moving picture projector, the combination'oi two helical gears adapted and arranged to mesh continuously with their aires at right angles, the first gear being mounted to rotate in a' :xed position. adjustable means for mounting the second gear, said means being slid' along its axis thereby preventing relative change in. angular velocity of said gears as said Second gear is moved along the axis of said iirst gear. 8.' In a gear train, the combination oi two helical gears adapted and arranged to mesh continuousiy with their axes at an angle, slidable means for mounting said gears so that one may move both axially and tangentially with respect to the other, and means whereby the resultant of said 4combined movements may be directed a-,ooavie parallel to the teeth oi said gears at their point of contact thereby preventing change in relative angular velocity o said gears as said movements tane piace.

u. in a moving picture projector employingoverlapping rotatable rectiiying elements, the combination of an aperture lrn sprocket, a shaft l whereon said nlm sprocket is fast mounted, a pair oi? helical gears mounted at an angle to each other and arranged to mesh continuously, said. gears being adapted and arranged to drive said sprocket, means whereby one of said gears is mounted, a two gear direct drive between one of'V I said shafts and the aperture feed sprocket of said projector, and meansfwhereby the position of said l aperture feed sprocket maybe adjusted with respeci: to said rectiiying elements without causing momentary change in angular velocity of saidY feed sprocket.

11.. In a moving picture projector employing overlapping rotatable rectifying elements, the combination of' av two gear direct drive between shafts whereon said rectifying elements are mounted, a two gear direct drive between one of said shafts and the aperture feed sprocket of said projector, means whereby the position of said aperture feed sprocket may be adjusted with respect to said rectifying elements without causing momentary change in angular velocity of said sprocket, and manual means for providing momentary acceleration and retardation of said sprocket.

, ARTHUR J. HOLMAN. 

